When we keep moving fast and thoughtlessly we don’t really develop ourselves as people and our lives can slip away. The same is actually true about developing the aerobic system that distinguishes the human animal as nature’s best endurance athlete.
When we make a few adjustments in our exercise habits and start doing some of the basic practices well we can start to develop our gift for endurance. In a previous post (How great athletes build unstoppable aerobic engines) we discussed how elite endurance athletes tend to do 80% of their training sessions at low intensities. Here we’ll discuss how to actually perform quality low intensity training. This is the single most important building block we use to develop endurance but very few people are actually doing this well. There are of course many other components and lessons to training endurance well, but low intensity endurance work is the basic dance move so let’s just start by learning that.
What does “low intensity” training mean? The science and coaching literature all generally points to the same answer: it’s the level of exercise intensity before lactate starts rising above baseline levels in our blood (we’ll refer to this as the “aerobic threshold” although the science uses a confusing inconsistency of terms). When lactate accumulates sufficiently in our blood we eventually need to slow down. Lactate buildup is a product of our anaerobic energy pathways which take over when our aerobic capacities are exceeded. When our aerobic systems are well developed, we can produce more energy from the oxidation of fat (which doesn’t produce lactate) and we can flush more of the metabolic compounds that lead to lactate buildup out of our blood (and in fact oxidize these as additional fuel). This is a metabolic adaptation and it appears to be the most trainable aspect of endurance performance. The aerobic threshold of an average person is usually somewhere between 50-60% of their maximum oxygen uptake, while for an elite endurance athlete it’s around 80% of maximum oxygen uptake. Those numbers actually illustrate two completely different metabolisms that place these two hypothetical people in entirely different dimensions of performance.
How can we determine our aerobic threshold? The only exact way to determine it is through lab testing at an exercise physiology lab. However, there are plenty of heart rate “zone” classifications that we can use to approximate it. They are all a bit different but they more or less line up and tend to point to the same figure. The simplest version is Dr. Phil Maffetone’s classic 180 - Age heart rate formula which essentially subtracts our age from 180 and then makes a couple modifications. Low intensity training means staying below the aerobic threshold, not attempting to stay exactly at this heart rate for an entire workout or to average this heart rate for an entire workout (which would require us to spend much time above the threshold). When I was training for ultra-endurance events I shot for 70-75% of my maximum heart rate in most of my training, which for me was safely lower than my aerobic threshold.
I’ve experimented with many different aspects of ultra-endurance training. Becoming disciplined about keeping my heart rate down for most of my training was one of the few changes that seemed to have a significant effect in helping me really improve as an endurance athlete. It can be quite helpful as we learn our bodies learn how to train at low intensities to use heart rate monitors. The monitors with chest straps tend to be more accurate than the purely wrist based monitors. Using heart rate monitors isn’t necessary, however. The aerobic threshold also tends to correspond to the intensity where we can still comfortably carry on a conversation and the intensity where we can still breathe entirely through our noses. I have personally found the heart rate monitor to be invaluable because is does a better job of reigning in my tendency to go too hard (90% of the time I use heart rate as a reminder to slow down). I tend to cheat on the conversational talk test by convincing myself that my choppy breathless sentences are still “easy conversation.” With the number on my heart rate monitor I can’t lie to myself like that.
At first it can be extremely frustrating to train like this. It usually feels too slow and we know we can go much faster. We’re so used to burning our shorter-lasting and higher intensity fuel systems that training our aerobic systems requires us to dramatically slow down. This is especially true for running. Hills that we used to run up we now find ourselves walking up. It’s also really hard if our heads are competitively wired or we’re really fixated on mileage or speed numbers. Friends (and frenemies) that we used to "beat" up hills can now either join us in the slow lane or wait for us. Our discipline must now be used to stick to our own game plan and trust it. This is just one of many ways that training is humbling. The key to making the switch and breaking free is acceptance of reality. When we spend our lives alternating between chairs and really hard efforts our aerobic systems are going to be underdeveloped so we will start slow. Using our anaerobic systems as a crutch to hide this reality and keep our speed numbers up will eventually catch up with us. Our aerobic systems are generally our weak links so the strategic move is to focus our attention there. Luckily our aerobic systems are highly trainable. After a few months speed eventually starts to return, only now at substantially easier effort levels that we can sustain for longer. That marks the beginning of real endurance ability that will help us go further in nature.
One thing that can help us cross this psychological chasm is periodically measuring our performance at our aerobic threshold over a fixed course. If we continue to keep getting faster every month on the same course at the same heart rate, we can know that the training is working, no matter how slow it feels. Eventually as we learn ourselves we’ll know what aerobic pace feels like inside ourselves and the outside world will just start flying by at a faster rate. I don’t really use my heart rate monitor anymore but I still occasionally use it to make sure my mind is still calibrated to keep me honest.
An important question is whether those of us who do not spend much time training (i.e., less than five hours per week) will also benefit from doing most of our training primarily at low intensities. We are no longer hunter gatherers on our feet all day. Elite endurance athletes often train 15+ hours per week so does a practice of mostly low intensity training also apply to time starved athletes? There’s quite a bit of controversy over this. There’s an understandable temptation to ditch all the low intensity volume work and just keep the high intensity “quality” work. However, what appears to be true is that from the perspective of long term aerobic development, the more important “quality” work is in fact the low intensity work. From the perspective of developing endurance performance, this question was studied and tested by a team of international sports scientists in 2013. Our best answer right now appears that recreational athletes with limited training time will also benefit from doing their training this way. It makes sense because the low intensity work is what actually practices the metabolic pathway that matters most. I will probably say this a million times in my life: we need to practice our aerobic system if we are ever to get fast relying on our aerobic system.
When we slow ourselves down a bit and stop chasing our highs it may help us remember what really matters. The most basic training tool in the endurance arsenal really helps us to clear out the noise in our lives and relax our grip on grinding training schedules, racing, logging numbers, and constantly pushing ourselves to exhaustion. Somewhat counter-intuitively (at least in this culture), focusing on slow work eventually makes us fast and strong over long distances. When we think about the lives of our ancestors this actually makes a lot of sense - most of our time was spent moving around fairly slowly. Furthermore, when we start looking at many indigenous tribes around the world what we tend to find is a tremendous ability to run far and run well. This is not only true for some outlier tribe like the Tarahumara in Mexico that was popularized in the book Born to Run. The ability to endure is nearly ubiquitous - being a great aerobic athlete is one of the main pillars of human survival. It is who we are.
Commentaires